middleware.ts

import { NextRequest, NextResponse } from 'next/server'

export const config = {
  matcher: [
    /*
     * Match all paths except for:
     * 1. /api routes
     * 2. /_next (Next.js internals)
     * 3. /_static (inside /public)
     * 4. /.well-known (inside /public)
     * 5. all root files inside /public (e.g. /favicon.ico)
     */
    '/((?!api/|_next/|_static/|.well-known/|_vercel|[\\w-]+\\.\\w+).*)',
  ],
}

export default async function middleware(req: NextRequest) {
  const url = req.nextUrl

  // Get hostname of request (e.g. demo.vercel.pub, demo.localhost:3000)
  const hostname = req.headers
    .get('host')!
    .replace('.localhost:3000', `.${process.env.NEXT_PUBLIC_ROOT_DOMAIN}`)

  // Get the pathname of the request (e.g. /, /about, /blog/first-post)
  const path = url.pathname

  // rewrites for app pages
  if (hostname == `app.${process.env.NEXT_PUBLIC_ROOT_DOMAIN}`) {
    return NextResponse.rewrite(
      new URL(`/app${path === '/' ? '' : path}`, req.url)
    )
  }

  // rewrite root application to `/home` folder
  if (
    hostname === 'localhost:3000' ||
    hostname === process.env.NEXT_PUBLIC_ROOT_DOMAIN
  ) {
    return NextResponse.rewrite(new URL(`/home${path}`, req.url))
  }

  // rewrite everything else to `/sell/[domain] dynamic route
  return NextResponse.rewrite(new URL(`/sell/${hostname}`, req.url))
}